Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the field of rickets and osteomalacia, progress has been made mainly in the mapping of vitamin D-dependency rickets or "pseudodeficiency rickets" type I to chromosome 12q14, and the further identification of a variety of abnormalities in the calcitriol receptor complex responsible for hereditary resistance to 1,25-dihydroxyvitamin D. The study of the molecular basis of this latter inherited disorder has important implications for a better understanding of the physiologic role of 1,25-dihydroxyvitamin D. Concerning osteopetrosis, the finding of a reverse transcriptase activity in a patient with the benign form of this disorder opens new perspectives such as the possibility that retroviral infection may be the origin of at least some type(s) of osteopetrosis. Moreover, impairment of macrophage colony-stimulating factor production appears to be a key event in the pathogenesis of the osteopetrotic op/op mutation in rodents.
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PMID:Rickets, osteomalacia, and osteopetrosis. 188 5

Hypovitaminosis D is a very common disorder, regarding both Western and developing countries. A growing amount of data over the last years have shown vitamin D deficiency to be high prevalent among HIV-positive subjects. In addition to "classic" risk factors, such as female sex, low dietary intake, dark skin pigmentation and low sun exposure, HIV-related factors, including immune activation and antiretroviral adverse effects, may affect vitamin D status. Even if both protease inhibitors and non-nucleoside reverse transcriptase inhibitors have been associated with low vitamin D levels, available evidences have failed to univocally associate hypovitaminosis D with specific antiretroviral class effects. Low vitamin D is known to have a negative impact not only on bone health, but also on neurocognitive, metabolic, cardiovascular and immune functions. Similarly to the general population, several studies conducted on HIV-infected subjects have associated hypovitaminosis D with a greater risk of developing osteopenia/osteoporosis and fragility fractures. Analogously, vitamin D deficiency has been described as an independent risk factor for cardiovascular disease and metabolic disorders, such as insulin resistance and type 2 diabetes mellitus. Last EACS guidelines suggest to screen for hypovitaminosis D every HIV-positive subject having a history of bone disease, chronic kidney disease or other known risk factors for vitamin D deficiency. Vitamin D repletion is recommended when 25-hydroxyvitamin D levels are below 10 ng/ml. Furthermore, it may be indicated in presence of 25OHD values between 10 and 30 ng/ml, if associated with osteoporosis, osteomalacia or increased parathyroid hormone levels. The optimal repletion and maintenance dosing regimens remain to be established, as well as the impact of vitamin D supplementation in preventing comorbidities.
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PMID:Vitamin D deficiency in HIV infection: an underestimated and undertreated epidemic. 2369 Jan 92

Vitamin D deficiency in HIV infection has attracted much interest. The best known clinical outcomes of vitamin D deficiency are rickets (children) and osteomalacia (adults). Several non-skeletal disorders have also been linked to suboptimal vitamin D levels in the general population. The prevalence of vitamin D deficiency varies widely (6-100%) across diverse patient populations, with no evidence that it is higher in HIV-positive versus noninfected adults. Vitamin D deficiency may blunt immune restoration and exacerbate HIV complications (e.g. opportunistic infections, poor perinatal outcomes, wasting, HIV disease progression, AIDS events, and death). The nonnucleoside reverse transcriptase inhibitor efavirenz was associated with a relatively high risk of vitamin D deficiency; nevirapine, etravirine, and rilpivirine were noted to have less or no impact on vitamin D versus efavirenz in the limited data available. Protease inhibitors have either no or a low association with vitamin D deficiency. Nucleoside/nucleotide reverse transcriptase inhibitors (with the possible exception of zidovudine) also did not appear to be associated with vitamin D deficiency. Management of vitamin D deficiency in HIV-positive adults has not been rigorously evaluated; some guidelines recommend more vitamin D supplementation for HIV-positive adults on antiretrovirals versus the general population (e.g. 2-3 times higher vitamin D daily intake for the age group; loading dose up to 10,000 IU/day for 8-10 weeks and a maintenance dose of 800-2,000 IU/day). In conclusion, although vitamin D deficiency in HIV-positive adults can be prevalent, current evidence for its causes and impact is relatively weak. More data, particularly from large, controlled, long-term trials, regarding the benefits of correcting vitamin D levels in HIV-positive adults are needed.
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PMID:Vitamin D deficiency in HIV: a shadow on long-term management? 2475 52